# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os
import collections

from paddle.io import Dataset

from paddle.utils.download import get_path_from_url
from paddle.dataset.common import md5file
from paddlenlp.utils.env import DATA_HOME
from . import DatasetBuilder

__all__ = ['PTB']


class PTB(DatasetBuilder):
    '''
    This is the Penn Treebank Project: Release 2 CDROM, featuring a million
    words of 1989 Wall Street Journal material.
    '''
    URL = 'https://bj.bcebos.com/paddlenlp/datasets/rnnlm/simple-examples.tgz'
    MD5 = "30177ea32e27c525793142b6bf2c8e2d"
    META_INFO = collections.namedtuple('META_INFO', ('file', 'md5'))
    SPLITS = {
        'train': META_INFO(
            os.path.join('simple-examples', 'data', 'ptb.train.txt'),
            "f26c4b92c5fdc7b3f8c7cdcb991d8420"),
        'valid': META_INFO(
            os.path.join('simple-examples', 'data', 'ptb.valid.txt'),
            "aa0affc06ff7c36e977d7cd49e3839bf"),
        'test': META_INFO(
            os.path.join('simple-examples', 'data', 'ptb.test.txt'),
            "8b80168b89c18661a38ef683c0dc3721")
    }

    def _get_data(self, mode, **kwargs):
        default_root = os.path.join(DATA_HOME, self.__class__.__name__)
        filename, data_hash = self.SPLITS[mode]
        fullname = os.path.join(default_root, filename)
        if not os.path.exists(fullname) or (data_hash and
                                            not md5file(fullname) == data_hash):

            get_path_from_url(self.URL, default_root, self.MD5)

        return fullname

    def _read(self, filename, *args):
        with open(filename, 'r', encoding='utf-8') as f:
            for line in f:
                line_stripped = line.strip()
                yield {"sentence": line_stripped}
